Question: Is Sand A Good Base For Concrete?

How deep should a sub base be for a concrete slab?

Concrete paths should be 75-100mm thick, whereas drives, garage bases or hardstandings should be at least 100mm thick.

For heavier use, such as large vans, use a 150-200mm thick concrete slab..

What size rebar should be used on a 4 slab?

Furthermore, what size rebar would be used on a 4 slab? For driveways and patios a #3 rebar which is 3/8 inch in diameter should be sufficient for the purpose. If you are constructing walls, piers or columns I recommend the use of #4 (1/2 inch) rebar. For building footings I would use a #5 (5/8 inch) rebar.

How do you fill under concrete?

A sand-cement grout can be used to fill voids under concrete slabs. This mix of sand, cement, and water is pumped through holes drilled to fill up the voids. While this method of slab jacking is cost-effective, there are major drawbacks to opting for this type of repair.

What kind of sand do you use for a concrete slab?

They generally sell two types, coarse (or concrete/sharp) sand and fine (builders/soft) sand. As the name implies the coarse (or concreting) sand contains less of the smaller particles than the soft sand. Coarse sand should only be used for concreting jobs and soft sand should only be used for render or mortar.

How many inches of gravel do you need for a concrete slab?

Excavate the slab area to a depth of about 7 inches, allowing 3 inches for a gravel base and 4 inches for concrete.

Can I use pea gravel under concrete?

Backfill beneath concrete flat-work along foundation walls should be accomplished with a granular material that is uniform in size. Some fill materials, such as round stones like pea gravel, tend to be self compacting. “I recommend open-graded granular material be used,” says Tull.

Should you wet sand before compacting?

Secondly wet it. … Moisture in your soil is vital to achieving proper compaction as the water helps slide soil particles together. Not enough moisture might lead to inadequate compaction; too much moisture will leave water-filled voids that weaken the soil’s load- bearing ability.

Is sand a good fill material?

Thanks to the nature of sand, fill sand doesn’t retain moisture and is great for promoting drainage in areas that are likely to get wet. It’s more aesthetically pleasing than fill dirt and therefore more suitable for exposed projects.

Is it cheaper to mix your own concrete?

One of the least expensive ways to get concrete is to mix your own. You can buy bags of the mix from a home improvement store. Typically, you only have to add water for it to be ready to pour. … Otherwise, you risk getting a weaker concrete once it cures, which could lead to cracks or crumbles within a couple of years.

What can I use for base under concrete?

Most concrete contractors want a mix of coarse and fine aggregate to create a compactable base that is going to be safe for settlement and drainage. Crusher run (a mix of crushed stone and stone dust) is one of the best base materials for concrete flatwork.

Do I need gravel under my concrete slab?

Whether you pour concrete for a walkway or patio, a strong gravel base is required to prevent the concrete from cracking and shifting. Gravel is especially important in clay soil because it doesn’t drain well, which results in water pooling under the concrete slab and slowly eroding the soil as it finally drains.

What is the best base for a concrete slab?

The base course material, according to ACI 302, “Concrete Floor and Slab Construction,” should be “compactible, easy to trim, granular fill that will remain stable and support construction traffic.” ACI 302 recommends material with 10 to 30% fines (passing the No. 100 sieve) with no clay, silt, or organic materials.

Can you pour concrete directly on dirt?

Long story short, yes you can pour concrete over dirt.

Is Clay a good base for concrete?

The clay can compress under the weight of the concrete, causing the slab to shift or sink over time. It also can leach moisture from the concrete itself, resulting in uneven curing and a brittle base. With proper preparation, however, it’s possible to pour a slab on clay soil without encountering these problems.

How much sand do I need for concrete base?

A concrete mix of 1 part cement : 2 parts sand : 4 parts coarse aggregate should be used for a concrete slab. Concrete must be placed within half an hour of mixing. Place your concrete into your formwork; work the concrete into awkward places and corners using a shovel or trowel.

Do you put plastic down before pouring concrete?

Here’s an idea—get rid of the sand and put the concrete right on the plastic sheet so that the bottom of the concrete mix does not dry out.

Do you need rebar for 4 inch slab?

No, you do not need rebar for a 4-inch slab of concrete on grade. A 4-inch-thick slab cast on the ground and in permanent contact with it will float and rebar is not required. Rebar is recommended on concrete measuring 5 – 6 inches thick.

How do you prepare the ground for a concrete slab?

Preparation is the most important aspect of pouring a concrete slab.Dig the ground down to the proper depth. … Smooth out the ground with the flat side of a rake so that you have a level surface. … Tamp the ground with a hand tamper or mechanical tamper. … Pour 2 inches of small, rounded gravel for additional drainage needs.

Can I use sand under concrete slab?

Because concrete slabs “float” on the soil, soft ground or voids underneath may cause unsupported areas to crack under heavy weight like vehicles. … of sand or gravel over clay and other poorly draining soils to provide even support.